Einstein

I have never once said that. As for your other point - The angle at which he ran resulted in a displacement vector of a few yards additional. I can break this down for you if you’d really like, but please PM me if so, I don’t want to derail this thread any more than I already have. If you’re in the Rochester area, I also have office hours at the University.

It’s called hyperbole. The thread is littered with pages and pages of people trying to explain away the slow speed at which he ran by his stumble. Which the math shows is not why he was so slow. did it make him slower? Yes. but it’s not the reason why he was slow in general.

This is instantaneous velocity. NOT speed over the course of a route. They are NOT THE SAME THING. Some offensive linemen have a terminal instantaneous velocity of 18/-19mph. Equivalent of a 4.3 to 4.5 second 40 yard dash. No, they’re not as fast as WR’s. They just have a high instantaneous velocity at peaks. I hate that the NFL publishes these stats without telling people what they actually mean. This is what some of have been advocating! But others refuse to believe he is anything but a speed demon lol.

It’s never a good idea to debate with people who do not have the base understanding to know when they are wrong. Without the base conceptual knowledge, they will just continue to argue on and on. We both knew better than to try. Butchering physics equations, not understanding what terminal velocity, not realizing that velocity is at its weakest during acceleration. On and on. Goodness, they don’t even realize that they’re contradicting themselves. Out of one side of their mouth they’re saying he was only slow because he stumbled. Then on the other side of the mouth, they’re using a mile per hour instantaneous velocity stat (that they don’t understand), to claim that he was fast. They don’t know what instantaneous velocity even is! They don’t understand how that differs from speed over the course of a run. It’s all so frustrating because they will argue nonstop while simultaneously being very wrong, but they don’t have the conceptual knowledge to realize that they’re wrong, so they just continue going on. I am always trying to learn something. So if someone has something to teach me, I am ready to accept that they are right. But most posters in this thread show that they don’t actually want to know what’s right, they just want to win an argument. Long story short: Leave them to their wrongness. I should have done so in the beginning. .

Uh, yes, they are. lol. A persons terminal velocity during a run is the velocity they reach at their peak. It is quite literally their TERMINAL velocity. YOU, as a lay person pretending to do physics, arguing against someone who does physics every day, are likely thinking that terminal velocity is related to the max speed in free fall - because that’s what popular culture taught you. You are very lost. The correct equation is v = v0 + a * t, not v = a * t. You’re ignoring the initial velocity entirely, which is basic physics 101. The stumbler starts with an initial velocity and that’s not wiped out by a brief stumble. lYou can’t just handwave away initial velocity and focus on acceleration. Your argument falls apart because you’re misunderstanding the fundamentals of motion. But even if you did, acceleration can be compared across two people simply by equaling the equations. We do know that. Then we can take the rate of change in Coleman from his get off to when he catches the ball, OR post stumble (after regaining). Which is what I did. Then we can compare it to during and after the stumble. some of you either never passed physics, or took it 20 years ago, and remember nothing. This is ridiculous. Like clockwork though, they will continue arguing.

Ugh, not this again. I really thought that you all learned this concept during the whole Derrick Henry debacle. This is terminal instantaneous velocity. Instantaneous velocity is NOT speed. An object can be slow and still have a high instantaneous velocity. Example: A large rock heaved from a catapult will travel slowly to its target. BUT it will have an extremely high instantaneous velocity. Velocity is the rate of change over time. So what the NFL does is they take a split second snapshot (aka, instaneous velocity), where a player moves from one yard to the next yard, and computes that on how long it took. Problem: This does not tell you speed! Like the catapult example, it tells you how fast they are moving in a split second at their highest peak.

I guess we agree after all!

Imagine trading a pick and taking on all that money just to score 15 points and drop to 2-5.

I don’t see the ball moving at all until the 3rd step. It looks pinned to his forearm.

Negative acceleration doesn’t cancel out initial velocity. Negative acceleration is simply a change in velocity in the negative direction. The stumbler still has a velocity greater than zero, which means they’re ahead, even if they lose a bit of speed. Meanwhile, the “static” (your word) runner is starting from zero and has to build speed from scratch. Acceleration doesn’t just compound endlessly … there’s a limit, and once terminal velocity is reached, the stumbler’s head start gives them a clear advantage. Put short and sweet; Your wrong but you don’t have enough conceptual background to realize it.

No his 3rd step is when the ball came out.

I think you’re starting to see why the others are wrong, but to answer your last sentence - it still doesnt. A “static” runner isn’t accelerating at all, so calling them static while talking about acceleration makes no sense. The correct term would be a runner starting from rest. If a stumbler already has v0 greater than 0, they’re already moving, so their total speed combines v0 and their acceleration. The idea that the static runner will accelerate faster is irrelevant because the stumbler already has an advantage in initial velocity. You’re focusing too much on acceleration without understanding how initial velocity and acceleration work together in building speed. Which is pretty much what most people do and it’s frustrating to someone who knows what they’re actually doing. Put another way: It would be like one runner starting from the block and another runner (his competitor), already running as he crosses the starting line but he has stumbled a second before that. Because he has an initial velocity, the non-stumbler would need much greater acceleration to beat him. Advantage stumbler.

For the 5th time, we are talking about his velocity AFTER he already re-establishes post stumble. After he gains his balance. After he accelerates again.

I guess i’m not seeing his hand off the ball on step 2. I see the ball not move until step 3.

There were 3 full feet down before ball came out though.

Excellent decision on your part.

But he DID have control when crossing the plane. The ball didn’t move until after he was in the endzone.

This makes absolutely zero mathematical or logical sense. Keon was not impeded from reaching top speed AFTER the stumble. You keep going back to the stumble but we are talking about a 3.37 second stretch that does not include the stumble. More on this below. This quote is telling you exactly what I have told you. Do you know what acceleration is? Do you understand why this quote is telling you that acceleration is the most important part? It is telling you this, because acceleration is the part of the race where a runner is at their SLOWEST. In other words, you stating that removing the block/stance portion of the race affects time is nonsensical - because it would only affect time in a negative way. By removing the block portion of a race, you are cutting out a significant slow curve and making their average velocity FASTER - not slower. Because Coleman had already accelerated post stumble, the calculation we have is higher than if he started off from a block. This is akin to asking: When have you ever been a professional baker, when telling someone that you made cookies for dinner. If anything, physics and mathematics are for more important in this discussion than your experience running.

I agree that it’s technically not a catch if it happens in the normal field of play. But I thought as soon as the ball crosses the goal line, it’s play over? Am I wrong on this? If a runner fumbles 1 centimeter after the ball breaks the plane, it’s a TD. Coleman had 2 feet down, ball broke the plane, and then it came out.

Bingo! And well said. And we can prove it with v = v0 + a(t). Because v is dependent on a and t, it is not possible for a runner to be at their fastest while still accelerating.

He wouldn’t need a push off because he has already accelerated. Think of it this way: When is a runner at their fastest? The beginning of a 40 yard dash? When they are pushing off the block? Or the second half of the race, when they have already accelerated? Consider the first kinematic equation of motion.

For the 4th time: And. That. Is. Why. The. Calculation. Was. Done. AFTER! He. Regained. Composure. And. Was. Running. Again. Not immediately after he was done stumbling. Physics and Math can explain anything on earth that is scalar or vector-driven. Yeah they’re assuming that because they’re not reading what i’m writing. Instead they’re jumping to defend. I took that into consideration, as I stated in the very first post on the 40 time. It either went over their head or they just skimmed the post in haste to respond.

Reading comprehension is at an all time low on this board, goodness gracious. Again: 1) The 40 time was taken AFTER he stumbled and regained composure. 2) All 40 times start from rest. Aka, the equivalent of the period you would have directly after a stumble. Math says you’re wrong but i’m guessing you wouldn’t believed it even I showed you.

For some players it is - for example, Derrick Henry ran a 4.3 40, in game, a couple weeks back.

I can’t tell if you’re joking. I said that calculation was taken AFTER he stumbled and regained his composure. It was a 4.99 second per 40 yard run AFTER he was back running, post stumble.